阅读下面的短文，从短文后各题所给的A、B、C和D四个选项中，选出可以填入空白处的最佳选项，。
How much do you laugh and smile during the day? Do you take your life and your illness or injury so 1 that there is no room for joy to fill you? Want a totally free, simple way to lift your 2 and improve your health with no medicine needed? Then laughing and smiling is 3 to you.
So laugh your way to happiness.4 it takes to put a smile on your face is what you should be doing. Research shows that laughing can increase the immune system,5 the body to stay disease free and fight colds and the flu.
If you are facing an illness, having a positive life opinion and a 6 of humor will keep your body open to healing. If you are healthy, laughing will help to make sure you stay that way, and can 7 enjoyment to your work and home life and 8 your daily stress.
Certainly, it can be 9 to keep a positive opinion of life all the time. Simply taking the time to 10 on the positive and treat for the good things 11 in your life can help 12, but if you are struggling with negative emotions that you just can't seem to 13, there are tools that can help.
There are so many things out there to smile about and 14 you have to do is find 15. Practice looking for the bright 16 of every situation. Avoid the negative: don't 17 yourself with your own problems—or 18 others for their “shortcomings”. And don't pay no attention to the joy in everyday things. Create your own “Laugh for Health”19 - anything to add to your collection and to give you fresh materials that 20 to you.
